基于棉花红边参数的叶绿素密度及叶面积指数的估算

    Estimation of cotton canopy chlorophyll density and leaf area index based on red-edge parameters

    • 摘要: 利用野外非成像高光谱仪,测试棉花两个品种4种配置种植方式两年关键生育时期的冠层反射光谱数据,应用光谱微分技术,获取棉花微分光谱680~750 nm波段的红边参数:红边面积(SDr)、红边斜率(Dr)以及红边位置(λr)变量;将棉花红边面积、红边斜率分别与其冠层叶绿素密度(CH.D)、叶面积指数(LAI)进行相关分析,它们的相关性均达到1%极显著水平,其中红边面积与叶绿素密度的相关性最好(RCH.D=0.8787**,n=137);并且红边面积较红边斜率对叶绿素密度、叶面积指数的预测精度更高。以棉花新陆早13号和19号为建模样本,通过红边面积与叶绿素密度的线性相关模型,分别反演新陆早13号、19号冠层叶片的叶绿素密度,结果表明对这两个棉花品种的叶绿素密度估算精度分别达87.4%和83.3%,说明高光谱红边参数是估算棉花叶绿素密度和叶面积指数的一种简单、快捷、非破坏性的有效方法。

       

      Abstract: Hyperspectral reflectance data were recorded at main growth stages of cotton in a field experiment including two cultivars with four planting patterns in two years study. By using spectral derivative analysis, red-edge parameters such as area of red edge (SDr), the slope of red edge value (Dr) and corresponding red edge position(λr)were obtained at bands of 680 nm to 750 nm, then the correlation between area of red edge, the slope of red edge and chlorophyll density (CH.D), leaf area index (LAI) were analyzed respectively. The results showed that they were all significant positive correlation at 1% lever; moreover, there was the highest correlation(RCH.D=0.8787**,n=137)between area of red edge and chlorophyll density. Using area of red edge to estimate chlorophyll density, leaf area index, the former had a higher precision than the latter did. Utilizing established model equation between area of red edge and chlorophyll density in cotton varieties of Xin Luzao No.19, Xin Luzao No.13 to derive their chlorophyll density, precision of estimated chlorophyll density of cotton two varieties were 87.4% and 83.3% respectively. The research shows that it is a simple, effective and non-destructive method to use red-edge parameters obtaining the canopy information of CH.D and LAI.

       

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